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TI-99/4A with PAL


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#51 adamantyr ONLINE  

adamantyr

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Posted Fri May 17, 2019 4:01 PM

Using the TI PAL modulator...

About the time the TI came out TV sets sold in the UK began to work well with a either a 50Hz or a 60Hz signal, as the tv sets were able to lock onto the frequencies well. My present CRT tv set is perfectly happy with an input of 50 or 60Hz.

There was a long standing issue in the UK with television sets made for the UK market not working too well with the UK TI99/4a. You could tune the TI sound in perfectly OR you could tune the TV picture in well. To get something approaching good meant VERY fine tuning of the tv channel, and if you got the sound perfect with no hum, the picture was probably rolling or there was colour loss etc.

This was designed in by TI. The PAL modulators were made for European PAL. The BBC chose to have their own version of PAL for the UK standard and there was a wider audio bandwidth. Or to put it another way, on the TI modulators of the day the sound channel was too close to the picture channel to play nicely with UK tv sets....

The UK used PAL STANDARD I while Europe used PAL STANDARD B or G - B and G used different bandwidths but the distance between image and sound was the same. The BBC wanted better quality sound so the sound channel in standard I was 0.50 MHz adrift of Standards B and G.,

I suspect this may be your problem with the RF signal. There is no ready answer except to tweak the fine tuning on the tv set- most sets had a manual fine tune opton. And compromise. Most folks preferred a good picture.

 

There's no fine tuning on this TV... just a channel detector. I ran that, it found 33 and 34 for the TI, and a bunch of digital channels. (Vizio, if it helps.)

 

Also, I think the fact it's B/W with splotchy artifacts of color is indicative that the color bands aren't being handled properly. Per "system information" it considers the channel 34 on antenna to be NTSC. So it's clearly NOT detecting it's a PAL signal or compensating. And no, there's no manual option to change it.

 

I think my last test here will be to acquire a PAL TV if I can (I'll know by Monday if I can get one), and test on that. It will require me to buy a transformer/converter for the TV.



#52 PeteE OFFLINE  

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Posted Fri May 17, 2019 4:20 PM

Wasn't your whole goal to get clearer video from a PAL TI?  That's not going to happen with the RF input to a TV of any kind.  From what I've read, you have modify the PAL RF modulator to get access to the composite signal, which you can then connect to that Magnavox studio monitor you have.  You can see where the composite signal is located in  the image in this post.  I would offer to do the modification for you, but I'm down in Portland, and you would need to bring the PAL TI and monitor to test.



#53 adamantyr ONLINE  

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Posted Yesterday, 9:16 AM

Wasn't your whole goal to get clearer video from a PAL TI?  That's not going to happen with the RF input to a TV of any kind.  From what I've read, you have modify the PAL RF modulator to get access to the composite signal, which you can then connect to that Magnavox studio monitor you have.  You can see where the composite signal is located in  the image in this post.  I would offer to do the modification for you, but I'm down in Portland, and you would need to bring the PAL TI and monitor to test.

 

Not actually, my goal was to SEE the TI running in a PAL format. Running on a regular TV using the modulator is fine, that's basically what every TI user in Europe had unless they heavily modded it or got some custom cable.

 

The TV I may be able to get looks like it's from Germany, so it should work with the standard PAL modulator which was optimized for the European standard and not the UK. Hopefully anyway. I'll find out Monday if I can get it.

 

Someone should really edit the top of this thread with a list of everything a U.S. 99'er would have to do to get a PAL TI working. It's not trivial.



#54 kl99 OFFLINE  

kl99

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Posted Yesterday, 1:10 PM

While some consumer NTSC TV sets support a PAL signal on their normal Video Inputs (Video Composite In, Y/C In, YUV In, Hdmi In, ...), I doubt there is a single one that can decode a high frequency modulated PAL signal (output of the PAL modulator) back down to a low frequency PAL signal. For this you would require a PAL compatible TV Tuner.

 

You have a higher chance to have success if you use the output from the 6 Pin DIN port directly. It is a YPbPr PAL signal. With some luck you might get an awesome flawless picture by going in to your Multinorm TV on its YUV Input. Or you modify a PAL modulator to output a low frequency Video Composite signal (still PAL, but now low frequency!).

 

The downside of using a PAL TI-99 is really the different speed when playing games. I wish you the best!



#55 ti99iuc ONLINE  

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Posted Yesterday, 4:17 PM

[...]

I'm not a hardware guy, though, so I'd have to find someone who could do the modification for me.

[...]

 

Hey friend, i built some cables,

 

Attached File  IMG_20190519_000637.jpg   116.79KB   0 downloads

 

tried on my monitor/TV and works great :)

 

Attached File  IMG_20190518_174847.jpg   161.65KB   0 downloads  Attached File  IMG_20190518_175100.jpg   61.02KB   0 downloads  Attached File  IMG_20190518_185141.jpg   182.09KB   0 downloads

 

If you think it could be help you PM me ;)



#56 apersson850 OFFLINE  

apersson850

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Posted Yesterday, 8:22 PM

Someone should really edit the top of this thread with a list of everything a U.S. 99'er would have to do to get a PAL TI working. It's not trivial.

Swedish citizenship?



#57 adamantyr ONLINE  

adamantyr

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Posted Today, 1:26 PM

 

Hey friend, i built some cables,

 

attachicon.gifIMG_20190519_000637.jpg

 

tried on my monitor/TV and works great :)

 

attachicon.gifIMG_20190518_174847.jpg  attachicon.gifIMG_20190518_175100.jpg  attachicon.gifIMG_20190518_185141.jpg

 

If you think it could be help you PM me ;)

 

I'll let you know. The problem is, even getting a component TV nowadays is a challenge, most TV's now only have a composite (if that) and HDMI.

 

That said, it's a nice cable, but I imagine the work involved plus the cost of international shipping may get up there a bit in price.



#58 adamantyr ONLINE  

adamantyr

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Posted Today, 4:53 PM

Okay, I got a PAL TV from Germany on it's way to me.

 

The TV is 230 volts, 50hz, 43 watts. Can anyone tell me exactly what kind of transformer or adapter I will need to power it safely please? Links to amazon or other sites are welcome.






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